If you use Beta or Nightly, you can turn on dev tools and use a custom addon list from a collection in your user account. https://blog.mozilla.org/addons/2020/09/29/expanded-extension-support-in-firefox-for-android-nightly/
There’s a remove ads option in the sidebar. It does not include Sync Ultra benefits such as user tagging, cloud backup, etc.
I do not see a way to hide them on mobile.
Connect has user tagging and is free